Study On Key Technologies Of Method And Instrument For Evaluating The Oil Yield Of Oil Shale By Infrared Spectroscopy

Oil shale is unconventional oil and gas resource of rich reserve, and known asalternative resources of oil. When it is heated in the absence of air or oxygen, oil shalecan produce shale oil which called synthetic oil. The exploitation of oil shale andother unconventional oil and gas resources has become the energy strategic focus ofall countries of the world. Oil shale reserve of our country ranks fourth in the world,and the mining of it have become increasingly urgent. However, the exploitation andutilization process of oil shale were restricted due to the low proven level.Oil yield is a key parameter to evaluate oil shale resource. The conventionalmethods used to measure oil yield from oil shale have a low efficiency, which restrictthe exploitation of oil shale. Infrared spectrometry with a fast speed, high sensitivity,and continuous measurement and many other advantages, has been widely used inmany fields for the qualitative or quantitative analysis of oil component. It has beenexpected to become a new method of fast measurement of oil yield from oil shaleon-site.This paper studies on the key technologies of infrared spectral method andcorresponding instruments to measure oil yield of oil shale. The specific contents asfollows:1. The near-infrared spectrosmetry was employed to evaluate oil yield of oil shale, inwhich the optimization algorithms including abnormal sample detection method,data pretreatment method, and wavelength selection method were studied to improvethe robustness and predictive ability of analysis model. Firstly, the PCA-MD andRHM were studied to identify and eliminate abnormal samples. By comparingpredictive ability of the model excluded abnormal samples, the results show that thePCA-MD has better recognition effect. Secondly, some data pretreatment methodswere studied to eliminate noises, and the SNV method has done the best. Thirdly, theCC, MWPLS and UVE were studied to select wavelengths, all the three algorithmsare able to simplify the model and improve the predictive ability of analysis model, in which UVE has more remarkable effect. Lastly, after excluding abnormal sample, datapretreatment and selecting wavelength, the PLS model, built by143wavelengths, hasgood predictive ability(RMSEP=0.825, RPD=2.389).2. The mid-infrared spectrometry with three wavenumber that coupled with carbontetrachloride extraction assisted by ultrasonic-assisted was used to measure the oilyield of oil shale, and mid-infrared transmission spectrometry with tabletting wasanalyzed and compared with it.The effect of extract concentration, extraction time andextraction temperature on extraction efficiency were optimized. The results show thatthe MLR model established by three absorbance picks (2855cm-1,2927cm-1and2955cm-1) has good performance(RMSEP=0.646, RPD=3.598). Analyzing the samebatch of oil shale samples by mid-infrared tabletting transmission method, after thespectral data pretreatment and wavelength selection, the PLS mode established by591wavenumbers has better prediction abiliy (RMSEP=0.370, RPD=6.283). Themid-infrared spectrometry has better performance than the near-infrared spectrometry,but has a relatively low efficiency and practicality. Finally, the near-infraredspectrometry was chosen and corresponding instruments were developed.3. A continuous adjustable power spectral band light source that covers the range of750~2500nm and has a cuvette had been developed. The light source adopts atungsten halogen lamp as the light emitting device and quartz lens to processgeometric optical transform. Transmission measurement was realized by the way ofvertical irradiation, and diffuse reflectance measurement was assisted by integralsphere.The performances of first3alignment light sources and imported light sourceswere tested and compared. The results show that the stability of our light source issimilar with imported light sources and it can be directly used for rapid and on-sitedetermination of oil yield in oil shale and subsequent quality analysis of shale oil.4. A short wave near-infrared fiber spectrometer was developed in this paper, whichcovers the spectral range of720~1080nm and selects the front illuminated CCDsensor. This work analyzes the structure of optical splitting system, gives theparameters of grating, collimating mirror and condensing mirror through theoreticalderivation and simulation. Usually, spherical aberration and coma are brought by theVI mirrors into optical splitting system, which had been corrected to improve the spectralresolution. This paper introduced the design of electrics and software of ourinstrument in detail, completed the controling system with low-power, high-speeddata acquisition and high stability, and developed the measurement software.Theexperiment results show that the parameters of our instrument as follows: wavelengthaccuracy is within0.16nm, spectral resolution is between0.75~1.25nm, SNR is in therange of268~345, linearity is good (R>0.998). Comparing with foreign instruments,the design and the production technology of our instrument is mature, which hasreached the level of commercial instrument and can be used for the quantitativeanalysis and measurement.5. A portable long wavelength near-infrared optical fiber spectrometer that with nomoving parts and can measure rapidly and efficiently was developed, the key designtechnologies of which were studied and introduced in this paper. Our instrument usesInGaAs photodiode array sensor of G9208-256W type, adopts the light structuredesign of crossing Czerny-Turner, uses ARM7microcontroller as the control center ofelectric design, and selects the fuzzy logic algorithm to achieve precise temperaturecontrolling. After testing, the results show that: the spectral range of the spectrometercovers the range of1180.3~2649.5nm, wavelength accuracy is less than5.8nm, thespectral resolution is between8.2~13.1nm, it can refrigeration to-20℃, SNR up to6719. The above results show that the instrument can be used to test oil yield of oilshale rapidly and on-site.The infrared spectrometry and corresponding instruments used to evaluate the oilyield of oil shale were developed and researched in-depth in this paper. Throughexperiments, the feasibility and the effectiveness of methods proposed has beenverified, which provide a theoretical reference for the follow-up researchers. Thebasic performance of instruments developed is equivalent to the foreign instruments,which lay instrument base for subsequent development of spectrometer. In addition,this paper describes the development schemes and test processes of instruments indetail, and studies in-depth of the key parts.For who engage in research anddevelopment of spectrometer, it has a good guidance and reference value.